Civil Engineering Reference
In-Depth Information
Table 4-4. Dual Flush Water Consumption
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NetWater
RatioofShortto
Consumption
(GPF)
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Office Building 1.7 to 1.0 1.10
Restaurant 1.3 to 1.0 1.15
Residential (Multi-Family) 4.0 to 1.0 0.96
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TypeofBuilding
LongFlushes
Thus, water savings over plumbing code requirements range
from 28% to 40%, depending on the type of building occupancy.
•
Waterless urinals save almost 95% water consumption, using water
only as part of routine maintenance wash-down. These devices have
been in use since the 1970s in Europe, but only arrived in the United
States in mid-1990s. Waterless urinals have been found to be more
hygienic than conventional ones since the aerosol effect by which
bacteria can be spread is eliminated.
Typically, these urinals utilize a trap insert filled with a propri-
etary sealant liquid instead of water. The lighter-than-water seal-
ant floats on top of the urine collected in the U-bend, preventing
odors from being released into the air. Other designs do not use a
cartridge; instead, using an outlet system that traps odors.
If waterless urinals are considered for retrofit projects, careful
evaluation of the existing waste piping is required. Carbon steel,
stainless or galvanized, will react with urine, which is slightly acid
(pH 4-6), resulting in accelerated corrosion. Therefore, old waste
piping systems that may contain galvanized steel piping should be
upgraded for waterless urinals. Copper, cast iron, and PVC piping
do not have corrosion issues with urine.
Maintenance of waterless urinals is somewhat greater than for
conventional urinals since routine cleaning and deodorizing (usu-
ally once per week) is required and the trap cartridges have to be
replaced periodically. Trap life depends on the number of uses,
typically around 7,000, not on the length of time it has been in use,
which makes it somewhat more difficult to establish a replacement
schedule. But, considering flush valve maintenance that is elimi-
nated with waterless urinals, there is little net increase in overall
maintenance requirements.
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